Browsing by Author "Ahmed Waseem, Waqas Waseem"
Now showing items 1-20 of 22
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Axisymmetric photonic structures with PT-symmetry
(International Society for Photo-Optical Instrumentation Engineers (SPIE), 2016)
Conference report
Open AccessPT-symmetric structures in photonic crystals, combining refractive index and gain-loss modulations is becoming a research field with increasing interest due to the light directionality induced by these particular potentials. ... -
Directionality fields generated by a local Hilbert transform
(American Physical Society, 2018-03-15)
Article
Open AccessWe propose an approach based on a local Hilbert transform to design non-Hermitian potentials generating arbitrary vector fields of directionality, ¿p(¿r), with desired shapes and topologies. We derive a local Hilbert ... -
Field concentration by Axisymmetric local PT-symmetry
(2016)
Conference report
Open AccessWe propose a new class of systems holding PT-symmetry only locally; the potential fulfills: U(r-r0)=U*(-r+r0 ) in a small neighborhood of any point r0, whereas on a global scale the system is only Parity symmetric: ... -
Genetic optimization Invents non-Hermitian potentials for Asymmetric Reflectivity
(2020-08)
Research report
Open AccessWe propose a general design strategy based on genetic optimization to realize asymmetric reflectivity in periodic and non-periodic planar structures containing dielectric and gain-loss layers. By means of an optimization ... -
Inverse-design of non-Hermitian potentials for light management
(International Society for Photo-Optical Instrumentation Engineers (SPIE), 2022)
Conference report
Open AccessIn this paper, we propose a general inverse-design strategy based on genetic algorithm optimization to achieve ‘on demand’ manipulation of light in one-dimensional (1D) and two-dimensional (2D) non-Hermitian systems. The ... -
Inverse-design of non-Hermitian potentials for on-demand asymmetric reflectivity
(2021-05-24)
Article
Open AccessWe propose a genetic algorithm-assisted inverse design approach to achieve ‘ondemand’ light transport in periodic and non-periodic planar structures containing dielectric and gain-loss layers. The optimization algorithm ... -
Locally parity-time-symmetric and globally parity-symmetric systems
(2016-11-11)
Article
Open AccessWe introduce a class of systems holding parity-time (PT) symmetry locally, whereas being globally P symmetric. The potential, U = U(vertical bar r vertical bar), fulfills PT symmetry with respect to periodically distributed ... -
PT-axisymmetric photonic nanostructures
(2016)
Conference report
Restricted access - publisher's policyOptical Parity-Time (PT-) symmetric systems support unusual properties. When the symmetric coupling between internal modes is broken the system becomes strongly unidirectional resulting in novel effects such as asymmetric ... -
PT-axisymmetric VCSELs with linear central defect
(Institute of Electrical and Electronics Engineers (IEEE), 2017)
Conference report
Open AccessSemiconductor Lasers and particularly Vertical-Cavity Surface-Emitting Lasers (VCSELs) are important laser sources used for many purposes. However, the applications of these lasers are mainly restricted by their strongly ... -
PT-axisymmetry for extraordinary field confinement
(International Society for Photo-Optical Instrumentation Engineers (SPIE), 2017)
Conference report
Open AccessOptical Parity-Time (PT-) symmetric systems support unusual properties when the symmetric coupling between internal modes is broken. We propose a new class of quasiperiodic PT-axisymmetric systems which lead to a simultaneous ... -
Regularization of broad-area lasers by non-Hermitian potentials
(2019)
Conference report
Open AccessIt was recently shown that arbitrary non-Hermitian optical potentials based on local Parity-Time (PT-) symmetry may control the flow of light, due to the asymmetric mode coupling. We propose periodic non-Hermitian potentials ... -
Regularization of vertical-cavity surface-emitting laser emission by periodic non-Hermitian potentials
(2019-08-15)
Article
Open AccessWe propose a novel physical mechanism based on periodicnon-Hermitian potentials to efficiently control the complexspatial dynamics of broad-area lasers, particularly in vertical-cavity surface-emitting lasers (VCSELs), ... -
Restricted Hilbert transform for feasible light management
(International Society for Photo-Optical Instrumentation Engineers (SPIE), 2021)
Conference report
Open AccessA feasible restricted Hilbert Transform (HT) is presented to solve the challenging practical realization of non-Hermitian systems, restricting the complex susceptibility within practical limits. Beyond closed-conservative ... -
Self-collimated beams in 2D complex periodic lattices from P- to PT-symmetry
(2017)
Conference report
Open AccessWe analyze self-collimation in two-dimensional periodic complex lattices. We consider P-symmetric and PT-symmetric complex lattices with different geometries, where the periodic modulations of both refractive index and ... -
Self-collimation in 2D Complex P- and PT-symmetric systems
(2017)
Conference report
Open AccessWe predict the self-collimation phenomena (or equivalently, dynamical localization) in 2-dimensional P-symmetric and PT-symmetric complex potentials, with periodic modulations of both gain/loss and refractive index. ... -
Self-collimation in PT -symmetric crystals
(AMER PHYSICAL SOC, 2017-05-10)
Article
Open AccessWe predict the self-collimation phenomena (or equivalently, dynamical localization) in two-dimensional PT-symmetric complex potentials, where the complex modulation is considered in the transverse, longitudinal, or ... -
Spatiotemporal stabilization proof of concept of Broad Area Semiconductor laser sources
(2018-02)
Research report
Open AccessWe provide a numerical proof of concept of a stabilization mechanism for BAS laser sources. The scheme is based on the simultaneous introduction of in-phase two-dimensional modulations on the refractive index and pump ... -
Stabilization of Broad Area Semiconductor Amplifiers and Lasers by Double Modulation of Pump and Refractive Index
(Institute of Electrical and Electronics Engineers (IEEE), 2018)
Conference report
Restricted access - publisher's policyBroad Area Semiconductor Amplifiers and Lasers display instability of the homogeneous state typically related with self-focusing nonlinearities, inducing multi-transverse mode operation and filamentation that deteriorates ... -
Stabilization of Broad Area Semiconductor Laser Sources
(Institute of Electrical and Electronics Engineers (IEEE), 2018)
Conference report
Open AccessWe numerically proof the stabilization of broad area semiconductor laser sources by introducing simultaneous in-phase two-dimensional modulations on the refractive index and on the pump (gain). We also examine the interplay ... -
Stabilization of broad area semiconductor lasers
(International Society for Photo-Optical Instrumentation Engineers (SPIE), 2018)
Conference report
Restricted access - publisher's policyBroad Area Semiconductor edge-emitting lasers typically display self-focusing nonlinearity due to the refractive index dependence on the population inversion. It induces the homogeneous solution instability, multi-transverse ...
